An investigation of Stress corrosion cracking in MgAZ61 alloy in 3.5% NaCl + 2% K 2 CrO 4 aqueous solution at room temperature

Effect of specimen orientation, heat treatment and applied potential on the stress corrosion susceptibility of magnesium AZ61 (Mg‐6.3% Al‐0.5% Zn‐0.20% Mn) alloy in an aqueous 3.5% NaCl + 2% K 2 CrO 4 solution at room temperature was investigated. Stress corrosion times to failure were measured at different values of initial stress intensities using single edge (pre) cracked sheet tensile specimens and a modified tensometer. It was observed that while the specimen orientation has a significant effect on the measured values of stress corrosion threshold stress intensity, K Iscc , the effect of varying the quench rate during heat treatment was minimal. Polarization measurements both in stressed and unstressed conditions, failed to reveal any significant effect of the applied stress intensity on the anodic polarization behavior of the alloy. However, measurements made under four different potentiostatic conditions showed a considerable increase in stress corrosion times to failure of the alloy. The results, together with fractographic observations of fractured specimen are discussed in terms of the mechanisms of stress corrosion cracking, in magnesium alloys.